The present invention relates generally to a vehicle body assembly and, more particularly, concerns a roof structure for a vehicle body.
Unitized vehicle body assemblies have been used for many years to provide motor vehicle design flexibility, ease of manufacturing, and satisfactory structural behavior.
With regard to the upper body structure of a vehicle body such as where the vehicle front header, roof side rail, and front A-pillar connect, it has been conventional to provide some sort of reinforcement structure. It is desirable that the roof front header panel and the roof side rails are rigidly connected with the A-pillar so as to form a rigid roof structure for the vehicle. In a typical vehicle roof structure, the cross-sectional profile of the front header, roof said rail and front A-pillar are all different. This normally occurs due to design considerations, particularly with respect to the roof ditch in the vicinity of the upper door frame and roof side rail. When the cross-sectional profiles differ among the roof header, roof side rail and A-pillar, it can be difficult to optimize the structural characteristics of the resulting joint because stresses are concentrated during static or dynamic loading in the region of the abrupt change in cross-sectional properties. Thus, there is a need for an improved vehicle roof structure having increased stiffness properties and improved structural characteristics compared to conventional joints connecting the roof header, roof side rail and body A-pillar.
The present invention provides an improved roof structure for a modular vehicle body. A vehicle roof structure in accordance with the present invention provides a joint between the roof header, roof side rail and A-pillar having a continuous substantially box-shaped cross-section thereby eliminating dramatic or abrupt changes in cross-sectional properties of the roof joint. The substantially continuous cross-section of the joint provides an efficient load path for applied stresses resulting in an even distribution of the static or dynamic loading event across all members of the joint.
In particular, the present invention provides a vehicle roof structure including a front header, a pillar support member, a side roof rail, and a roof rail outer front member. The front header has a substantially box-shaped cross-section. The pillar support member has an elongated member extending between a windshield opening and a door opening, a short first member at one end of the elongated member extending along the windshield opening, and a short second member at the end extending along the door opening. The first member includes a first edge adjoining an end of the front header. The side roof rail has a substantially box-shaped cross-section and adjoins a second edge of the pillar support second member. The roof rail outer front member is affixed to the pillar support member. The roof rail outer front member adjoins the end of the front header in a region of the first edge, adjoins the side roof rail in a region of the second edge, and extends along at least a portion of the elongated member of the pillar support member. The roof rail outer front member and the pillar support member form a substantially box-shaped cross-section extending between the first, second and elongated members such that a continuous substantially box-shaped cross-section exists throughout the joint defined by the vehicle roof structure.
In another embodiment, a vehicle roof structure is provided that includes a front header, a side roof rail, a pillar support member and a roof rail outer front member. The front header includes an inner front header and an outer front header joined together along a respective windshield flange and a respective roof flange. An end of the inner front header is offset with respect to an end of the outer front header. The front header also has a substantially box-shaped cross-section. The side roof rail includes a roof rail inner rear member and a roof rail outer rear member joined together along a respective door opening flange and a respective roof flange. An end of the roof rail inner rear member is offset with respect to an end of the roof rail outer rear member. The side roof rail also has a substantially box-shaped cross-section. The pillar support member adjoins the end of the inner front header and the end of the roof rail inner rear member. It also includes an elongated member extending between a windshield opening and a door opening. The roof rail outer front member is affixed to the pillar support member, the outer front header and the roof rail outer rear member. The roof rail outer front member extends along at least a portion of the elongated member. The roof rail outer front member and the pillar support member form a substantially box-shaped cross-section that extends between the ends of the inner and outer front headers and the ends of the roof rail inner and outer rear members, and extends along the elongated member such that a continuous substantially box-shaped cross-section exists throughout the joint defined by the vehicle roof structure.
One advantage of the vehicle roof structure according to the present invention is its increased stiffness properties versus conventional joints. This results from the substantially continuous cross-section throughout the joint. In addition, the overall noise vibration and harshness (NVH) performance of the resulting vehicle is improved as well. The resulting safety cage formed by the roof structure can also have improved crash-worthiness.